178 List of Acronyms AIC: Akaike’s Information Criterion CI: Confidence Interval COSMIN: Consensus-based Standards for the selection of health Measurement Instruments CRT: Chemo Radiation Therapy EORTC QLQ-C30: European Organization for the Research and Treatment of Cancer Quality of Life Questionnaire EORTC QLQ-H&N35: European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Head and Neck module FEES: Fibreoptic Endoscopic Evaluation of Swallowing GRIX: Groningen RadiotherapyInduced Xerostomia scale HNC: Head and Neck Cancer HPV: Human Papilloma Virus ICC: Intraclass Correlation Coefficient IQR: Inter Quartile Range LMM: Linear Mixed Model LoA: Limits of Agreement MAI: Mixing Ability Index MAT: Mixing Ability Test MDADI: M.D. Anderson Dysphagia Inventory NET-QUBIC: NETherlands QUality of life and BIomedical Cohort studies in head and neck cancer N/A: Not Applicable OAR: Organs at Risk PORT: Post-Operative Radiation Therapy PRO: Patient Reported Outcome QoL: Quality of Life REML: Restricted Maximum Likelihood approach ROC: Receiver Operating Curve RT: Radiation Therapy SD: Standard Deviation SDC: Smallest Detectable Change SE: Standard Error SEM: Standard Error of Measurement SPSS: Statistical Package for the Social Sciences SWAL-QoL: Swallowing Quality of Life Questionnaire TNM: Tumor Node Metastasis (classification system) UMCU: University Medical Center Utrecht UW-QoL: University of Washington Quality of Life questionnaire WST: Water Swallowing Test